Mechanisms of graft-versus-leukemia effects after allogeneic stem cell transplantation: effects on the leukemia stem cell?
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The 2023 EBMT report on hematopoietic cell transplantation and cellular therapies. Increased use of allogeneic HCT for myeloid malignancies and of CAR-T at the expense of autologous HCT
In 2023, 47,731 HCT (20,485 (42.9%) allogeneic and 27,246 (57.1%) autologous) in 43,902 patients were reported by 696 European centers. 6042 patients received advanced cellular therapies, 4888 of which were CAR-T. Compared to the previous year there was an increase in CAR-T (+52.5%), in allogeneic HCT (+7.8%) but none in autologous HCT (+0.4%). Main indications for allogeneic HCT were myeloid (11,748; 60.7%), lymphoid malignancies (4,850; 25.0%), and non-malignant disorders (2558; 13.2%). Use of allogeneic HCT increased for AML (+12.1%) and for NHL (+11.0%), particularly in T-NHL (+25.6%). Main indications for autologous HCT were lymphomas (7890; 32.2%), PCD (14,271; 58.2%), and solid tumors (1608; 6.6%) with recovering numbers for autoimmune diseases. In patients with allogeneic HCT, the use of sibling donors increased by +1.0%, haploidentical donors by +11.7%, and unrelated donors by +11.1%. Cord blood HCT decreased again by −5.4%. Pediatric HCT activity increased slightly (5455; +0.1%) with differences between allogeneic (4111; −0.5%) and autologous HCT (1344: +1.7%). Use of CAR-T increased to a cumulative total of 13,927 patients including patients treated for autoimmune diseases. Overall, numbers show a complete recovery from the pandemic dip with increased cellular therapy at the expense of autologous HCT. Allogeneic HCT activity focuses on myeloid malignancies.
Donor MHC-specific thymus vaccination allows for immunocompatible allotransplantation
Organ transplantation is the last-resort option to treat organ failure. However, less than 10% of patients benefit from this only option due to lack of major histocompatibility complex (MHC)-matched donor organs and 25%–80% of donated organs could not find MHC-matched recipients. T cell allorecognition is the principal mechanism for allogeneic graft rejection. We herein present a “donor MHC-specific thymus vaccination” (DMTV) strategy to induce T cell tolerance to both autologous and allogeneic donor MHC. Allogeneic MHC molecules were expressed in the recipient thymus through adeno-associated virus-mediated delivery, which led to stable expression of allogeneic MHC together with the autologous MHC in the engineered thymus. During local T cell education, those T cells recognizing either autologous MHC or allogeneic MHC were equally depleted. We constructed C57BL/6-MHC and BALB/c-MHC dual immunocompatible mice via thymus vaccination of C57BL/6-MHC into the BALB/c thymus and observed long-term graft tolerance after transplantation of C57BL/6 skin and C57BL/6 mouse embryonic stem cells into the vaccinated BALB/c mice. We also validated our DMTV strategy in a bone marrow, liver, thymus (BLT)-humanized mouse model for immunocompatible allotransplantation of human embryonic stem cells. Our study suggests that the DMTV strategy is a potent avenue to introduce a donor compatible immune system in recipients, which overcomes the clinical dilemma of the extreme shortage of MHC-matched donor organs for treating patients with end-stage organ failure.
Reducing functionally defective old HSCs alleviates aging-related phenotypes in old recipient mice
Aging is a process accompanied by functional decline in tissues and organs with great social and medical consequences. Developing effective anti-aging strategies is of great significance. In this study, we demonstrated that transplantation of young hematopoietic stem cells (HSCs) into old mice can mitigate aging phenotypes, underscoring the crucial role of HSCs in the aging process. Through comprehensive molecular and functional analyses, we identified a subset of HSCs in aged mice that exhibit “younger” molecular profiles and functions, marked by low levels of CD150 expression. Mechanistically, CD150low HSCs from old mice but not their CD150high counterparts can effectively differentiate into downstream lineage cells. Notably, transplantation of old CD150low HSCs attenuates aging phenotypes and prolongs lifespan of elderly mice compared to those transplanted with unselected or CD150high HSCs. Importantly, reducing the dysfunctional CD150high HSCs can alleviate aging phenotypes in old recipient mice. Thus, our study demonstrates the presence of “younger” HSCs in old mice, and that aging-associated functional decline can be mitigated by reducing dysfunctional HSCs.
Evolution of temporomandibular joint reconstruction: from autologous tissue transplantation to alloplastic joint replacement
The reconstruction of the temporomandibular joint presents a multifaceted clinical challenge in the realm of head and neck surgery, underscored by its relatively infrequent occurrence and the lack of comprehensive clinical guidelines. This review aims to elucidate the available approaches for TMJ reconstruction, with a particular emphasis on recent groundbreaking advancements. The current spectrum of TMJ reconstruction integrates diverse surgical techniques, such as costochondral grafting, coronoid process grafting, revascularized fibula transfer, transport distraction osteogenesis, and alloplastic TMJ replacement. Despite the available options, a singular, universally accepted ‘gold standard’ for reconstructive techniques or materials remains elusive in this field. Our review comprehensively summarizes the current available methods of TMJ reconstruction, focusing on both autologous and alloplastic prostheses. It delves into the differences of each surgical technique and outlines the implications of recent technological advances, such as 3D printing, which hold the promise of enhancing surgical precision and patient outcomes. This evolutionary progress aims not only to improve the immediate results of reconstruction but also to ensure the long-term health and functionality of the TMJ, thereby improving the quality of life for patients with end-stage TMJ disorders.
Stem cell transplantation extends the reproductive life span of naturally aging cynomolgus monkeys
The ovary is crucial for female reproduction and health, as it generates oocytes and secretes sex hormones. Transplantation of mesenchymal stem cells (MSCs) has been shown to alleviate pathological ovarian aging. However, it is unclear whether MSCs could benefit the naturally aging ovary. In this study, we first examined the dynamics of ovarian reserve of Chinese women during perimenopause. Using a naturally aging cynomolgus monkey (Macaca fascicularis) model, we found that transplanting human embryonic stem cells-derived MSC-like cells, which we called M cells, into the aging ovaries significantly decreased ovarian fibrosis and DNA damage, enhanced secretion of sex hormones and improved fertility. Encouragingly, a healthy baby monkey was born after M-cell transplantation. Moreover, single-cell RNA sequencing analysis and in vitro functional validation suggested that apoptosis, oxidative damage, inflammation, and fibrosis were mitigated in granulosa cells and stromal cells following M-cell transplantation. Altogether, these findings demonstrate the beneficial effects of M-cell transplantation on aging ovaries and expand our understanding of the molecular mechanisms underlying ovarian aging and stem cell-based alleviation of this process.
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